In this Article


There are several different inborn errors of metabolism. Symptoms will depend on the specific condition. Metabolic disorders often cause a variety of signs and symptoms. Common symptoms include:

  • Unintended weight loss, or a failure to gain weight and grow in babies and children
  • Tiredness and lack of energy
  • Hypoglycemia or low blood sugar
  • Poor feeding habits
  • Stomach problems or vomiting
  • High levels of acid or ammonia in the blood
  • Abnormal liver function
  • Developmental delays in babies and children
  • Seizures or other central nervous system problems

When to See a Doctor

Your newborn was likely screened for some metabolic disorders at birth. However, see a doctor if you notice and signs or symptoms of a metabolic disorder. Early treatment of inborn errors of metabolism is key to preventing long-term health problems.


Inborn errors of metabolism are genetic, meaning they are inherited and are often present at birth. A gene that tells the body how to do a certain metabolic process or make an enzyme gets changed (mutates).

Diagnosis and Tests

Newborn screening tests are given at birth that can identify some inherited metabolic diseases. Because there are many conditions that can show a variety of symptoms, your doctor may use more than one test. A test that shows abnormal results will be followed with a second test to confirm the diagnosis.

Most tests are done to a urine or blood sample to detect amino acids or other substances that might be present in the body. For a few disorders, your doctor might need to do a test on tissues from the liver, brain, muscles, bone marrow, or skin; or they may request specific DNA testing.


Treatment for metabolic disorders depends on the specific disorder. Common treatments include:

  • Changes to diet and lifestyle. You may have to avoid certain foods that the body can’t handle and break down.
  • Medicines. Medicines may be used to control certain symptoms, help your feel better, and avoid life-threatening emergencies.
  • Enzyme replacement therapy. Injections of a missing or low enzyme may help treat certain disorders.


Because these diseases are inherited, you can’t prevent them. However, pregnant women can take some precautions to ensure the best possible outcomes for their babies:

  • Taking folic acid (a B vitamin) for at least a month before and throughout pregnancy, which can help prevent major birth defects of the brain and spine
  • Letting your doctor and other healthcare providers know that you are pregnant or planning to become pregnant
  • Avoiding exposure to radiation
  • Avoiding harmful substances, such as illegal drugs, alcohol, and smoking
  • Asking your doctor or pharmacist about potential side effects or dangers to pregnant women of over-the-counter and prescription drugs
  • Taking care of yourself by maintaining a healthy diet and properly managing diabetes, if applicable
  • Preventing infections, as possible, with healthy practices such as cooking meat thoroughly, washing your hands often, and trying to stay away from people who are sick

What is an Inborn Errors of Metabolism?

Inborn errors of metabolism are rare genetic disorders that affect the body’s metabolism. Metabolism [meh-TAB-uh-lih-zem] describes the body’s ability to convert food and drink into energy, as well as get rid of certain wastes made during that process. It’s a complex process that uses many different chemicals, enzymes, hormones, cells, and organs to work properly.

Enzymes are special proteins that cause chemical reactions. When we eat, the digestive system uses enzymes to break down the food into sugars, amino acids, fatty acids, and other chemicals that can be used by the body. The body uses these chemicals as fuel or energy, as well as to build or repair tissues. Anything that can’t be used by the body is waste. Enzymes can also help convert or break down wastes so they can be removed from the body.

With inborn errors of metabolism, certain enzymes don’t work properly or the body doesn’t make enough of an enzyme. This disrupts the process of metabolism. The body may be blocked from using substances it needs to function. Or, waste substances can build up in the body and become toxic. These issues can cause health problems, including serious developmental problems in young children.

Inborn errors of metabolism are genetic, meaning they are inherited and are often present at birth. Newborns are screened for several serious conditions, including metabolic, hormone, and blood disorders. Early detection and treatment of certain disorders can prevent lifelong health problems.

There are several different inborn errors of metabolism, including:

  • Fructose intolerance
  • Gaucher disease
  • Maple sugar urine disease (MSUD)
  • Phenylketonuria (PKU)
  • Urea Cycle Disorder (UCD)